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Database Management: Getting Data Together. Chapter 14. Objectives. Describe the hierarchy of data Explain the differences between files and databases List the four database models Describe the concept of data integrity Describe the functions of a database management system

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Database Management: Getting Data Together

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Database Management: Getting Data Together

Chapter 14


Objectives

  • Describe the hierarchy of data

  • Explain the differences between files and databases

  • List the four database models

  • Describe the concept of data integrity

  • Describe the functions of a database management system

  • Describe the process of creating a database in general terms

  • Compare and contrast relational and object-oriented databases

  • Explain what a data warehouse is an how it differs from a database


Contents

  • Computer Databases

  • Database Management Systems

  • The DBMS Process

  • Concurrency Control

  • Security

  • Backup and Recovery

  • Looking at the Data


Computer Databases

  • Track information

  • Keep consistent standards

  • Allow higher productivity as a result of better information


Hierarchy of Data

  • Field

    • Smallest meaningful unit of data

    • Group of one or more characters that has a specific meaning

  • Record

    • Set of fields containing all information known about one entity

    • Each record contains the same fields in the same sequence

  • File

    • Collection of related records


Hierarchy of Data


File Processing

  • File processing

    • Data redundancy

  • Database models reduce redundancy

    • Saves storage space

    • Saves update effort

      • Time

      • Accuracy


Database Models

  • Database Types

    • Relational

    • Object-oriented

    • Hierarchical

    • Network

  • Each type structures, organizes and uses data differently


RDBMSRelational Database Management System

  • Organizes data into related tables (files)

  • Table consists of rows and columns

  • Tables linked based upon a common field (key)


RDBMSKey

  • Primary key

    • A field whose value uniquely identifies a record

  • Foreign key

    • Primary key of another table

    • Used as link to other table

    • May have duplicate values


OODBMSObject-Oriented Database Management System

  • Manipulates object-oriented databases

  • Object – represents a real-world entity

    • Attributes / properties

      • Data about the entity

    • Methods / Actions

      • Operations that work the data


OODBMSObject-Oriented Database Management System

  • Compared to RDBMS

    • More complex

    • Steeper learning curve

    • Skilled employees needed who earn high pay

  • Combined Object/relational DBMS

    • Relational database that incorporates some complex data types


Data Integrity

  • Degree to which data is accurate and reliable

  • Integrity constraints – rules

    • Acceptable values for a field

    • Primary key values

    • Foreign keys

  • Integrity constraints must be enforced when data is entered or data is unreliable


DBMSDatabase Management System

Levels of software

  • Sophisticated

    • Mainframe

    • Expensive – tens of thousands of dollars

    • Complex

    • Planned and managed by computer professionals

  • Simple

    • PC

    • Inexpensive – few hundred dollars

    • User can set up and use the database


DBMSDatabase Management System

Basic functions

  • Create a database

  • Enter data

  • Modify the data as required

  • Retrieve information from the database


DBMSCreate a Database

  • Data Dictionary / Catalog

    • Stored data about the tables and fields within the database

  • Per table

    • Table name

    • Relationships

  • Per field

    • Field name

    • Data type

    • Field size

    • Validation rules


DBMSEnter and Modify Data

  • Operations

    • Adding new data

    • Modifying data

    • Deleting data

  • Methods

    • User interacts directly with DBMS

    • Programs written by professional programmers access the data using special commands built into the DBMS


DBMSData Retrieval

  • Extracting the desired data from the database

  • Primary forms

    • Queries

    • Reports


Query

  • Ask a question about the data

  • Present criteria that selects data from the database

  • Results in smaller portion of the database

  • Query Language

    • Prepare your query using English-like statements

    • Proprietary query language in DBMS


Query

SQLStructured Query Language

Entered directly by user

Included in programs

QBE

Query-by-Example

Graphical interface to specify your criteria


Report

  • Formatted presentation of data from the database

  • Normally printed

  • Designed using a report generator


The DBMS Process

Review the data and edit until accurate

Describe the data

Enter the data


The DBMS Process

The Plan…

The Report…


Concurrency Control

  • Databases are used concurrently by many users

  • Problem if several users attempt to update the same record at the same time

  • Record locking

    • First user requests record

    • Others are locked out for update


Concurrency Control


Security

  • Data is stored in a central location

    • Problem: unauthorized access is major concern

    • Benefit: easier to apply security measures

  • Features

    • User ID and password

    • Privileges assigned to each user

      • Read-only

      • Update


Backup and Recovery

  • Why?

    • Data can be accidentally damaged or destroyed

    • Hardware can fail

    • Forces of nature can cause physical damage

    • Software or human errors can corrupt data

  • Backup – copy made periodically

  • Recovery – replaces the damaged database with the good backup


Looking at the DataOLTP – Online Transaction Processing

  • Supports day-to-day database activities

  • Little support for data analysis


Looking at the DataData Warehouses

  • Databases designed to support ongoing operations

  • Data is captured from the db

    • Summary form

    • Scheduled basis

    • Period of time

  • May include data from external sources


Looking at the DataData Warehouses

  • Online Analytical Processing (OLAP)

    • Analyzes the data

    • Produces information for managers

  • Data mining

    • Statistical and artificial intelligence techniques

    • Look for unrecognized

      • Patterns

      • Relationships

      • Correlations

      • Trends

    • Helps managers make strategic business decisions


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